Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.Additional co-authors: G. MacMillan, M. Rautio, K. M. Walter Anthony, and K. P. Wicklan

High methylmercury in Arctic and subarctic ponds is related to nutrient levels in the warming eastern Canadian Arctic

Permafrost thaw ponds are ubiquitous in the eastern Canadian Arctic, yet little information exists on their potential as sources of methylmercury (MeHg) to freshwaters. They are microbially active and conducive to methylation of inorganic mercury, and are also affected by Arctic warming. This multiyear study investigated thaw ponds in a discontinuous permafrost region in the Subarctic taiga (Kuujjuarapik-Whapmagoostui, QC) and a continuous permafrost region in the Arctic tundra (Bylot Island, NU). MeHg concentrations in thaw ponds were well above levels measured in most freshwater ecosystems in the Canadian Arctic (>0.1 ng L−1). On Bylot, ice-wedge trough ponds showed significantly higher MeHg (0.3−2.2 ng L−1) than polygonal ponds (0.1−0.3 ng L−1) or lakes (<0.1 ng L−1). High MeHg was measured in the bottom waters of Subarctic thaw ponds near Kuujjuarapik (0.1−3.1 ng L−1). High water MeHg concentrations in thaw ponds were strongly correlated with variables associated with high inputs of organic matter (DOC, a320, Fe), nutrients (TP, TN), and microbial activity (dissolved CO2 and CH4). Thawing permafrost due to Arctic warming will continue to release nutrients and organic carbon into these systems and increase ponding in some regions, likely stimulating higher water concentrations of MeHg. Greater hydrological connectivity from permafrost thawing may potentially increase transport of MeHg from thaw ponds to neighboring aquatic ecosystems

L’éclosion de la gérontopsychiatrie à l’Université de Montréal, une histoire à découvrir

La gérontopsychiatrie est une surspécialité de la psychiatrie qui s’intéresse à l’évaluation, au diagnostic et au traitement des troubles mentaux complexes chez les personnes âgées. Fait méconnu, son histoire encore jeune est fortement liée, au Québec, à celle du Département de psychiatrie de l’Université de Montréal (UdeM) et son réseau d’hôpitaux d’enseignement : dès la fin des années 1970, le premier service de gérontopsychiatrie a vu le jour à l’Institut universitaire en santé mentale de Montréal, et la première clinique externe au Pavillon Albert-Prévost. Le Centre hospitalier de l’Université de Montréal, l’Hôpital Maisonneuve-Rosemont et l’Institut universitaire de gériatrie de Montréal ont développé par la suite des services de gérontopsychiatrie à leur image. Le département de psychiatrie de l’UdeM est aussi le premier au Québec à offrir un programme de résidence en gérontopsychiatrie agréé par le Collège royal des médecins et chirurgiens du Canada, et ce depuis 2014. La gérontopsychiatrie est un domaine en plein essor, et les défis sont multiples dans le contexte démographique actuel. Pourtant, des obstacles majeurs freinent son développement sur le plan clinique, de l’enseignement et de la recherche, en particulier l’absence de postes spécifiques et protégés en gérontopsychiatrie. La restructuration majeure du réseau de la santé au Québec en 2015 est un autre point d’incertitude. Ce cinquantenaire du département de psychiatrie est une occasion de souligner l’apport majeur de l’UdeM au développement de la gérontopsychiatrie au Québec, et d’insister sur la spécificité des besoins des aînés en matière de soins et de services en santé mentale.Objectives: Geriatric psychiatry became an official psychiatric subspecialty in Canada in 2009. The first board examinations from the Royal College of Physicians and Surgeons of Canada (RCPSC) took place in 2013. Geriatric Psychiatry focuses on the assessment, diagnosis, and treatment of complex mental disorders in late life, a time when the interface between physical and mental health issues often adds a new level of complexity.Little has been written on the history of geriatric psychiatry in Québec and in Canada. A lesser-known aspect is that from the 1970’s onwards, the department of psychiatry at the Université de Montréal (UdeM) and its network of teaching hospitals have played a pioneering role in the development of geriatric psychiatry services and training. We seek to recount the history of geriatric psychiatry at UdeM, by tracing the milestones and identifying the main actors responsible for its development, from the inception of the department of psychiatry 50 years ago. This leads us to share reflections on some of the issues geriatric psychiatry is facing in Québec.Methods: We interviewed several key actors, past and present, of geriatric psychiatry at UdeM. We read through relevant sources such as articles and monographs on the local history of psychiatric services, information bulletins and annual reports from hospitals and from UdeM, as well as other documentation from personal archives.Results: One of the very first geriatric psychiatry services in Canada was founded in 1978 at the Institut universitaire en santé mentale de Montréal, with a dedicated inpatient unit for new admissions of elderly psychiatric patients. A geriatric psychiatry outpatient clinic was inaugurated the same year at the Pavillon Albert-Prévost. Throughout the years, geriatric psychiatry services were also developed in the remaining hospital sites affiliated with the department of psychiatry at the UdeM (Hôpital Maisonneuve-Rosemont, Centre hospitalier de l’Université de Montréal, Institut universitaire de gériatrie de Montréal), driven by dedicated individuals, in accordance with their respective historical background and mission. Clinical training is provided in each of these sites for medical students, psychiatry residents and more recently, for future geriatric psychiatrists. In 2014, the geriatric psychiatry residency program at UdeM was the first to be accredited in Québec by the RCPSC, as well as the first French language geriatric psychiatry program in North America.Conclusion: Geriatric psychiatry in 2015 is a burgeoning field, in a challenging demographic context. Despite the clinical need, major obstacles remain, particularly in the absence of specific geriatric psychiatry positions. Furthermore, the Québec healthcare system is going through a major restructuration in 2015, adding to the uncertainty. The 50th anniversary of the department of psychiatry at UdeM is an opportunity to underline the contribution of UdeM to the development of geriatric psychiatry in Québec, and to emphasize the specific needs of the elderly in terms of mental health care and geriatric psychiatry services